Failure of systemically administered adenine arabinoside to affect humoral and cell-mediated immunity

The effect of a high dosage (250 mg/kg of body weight) of adenine arabinoside or ara-A (9-beta-D-arabinofuranosyladenine) on humoral immunity was studied in New Zealand white rabbits infected with the McKrae strain of herpes simplex virus. The rabbits were treated daily for 14 days with subcutaneous injections of ara-A. The primary and secondary humoral responses, as measured by neutralizing antibody titers, developed similarly in control and treated groups. Similar drug treatment was used on guinea pigs before or after sensitization with BCG vaccine. Subsequent challenge of the sensitized animals with Old tuberculin solution indicated that ara-A treatment had no effect on the induction or previously established cell-mediated immunity. The lack of immunosuppressive activity of ara-A at dosage levels higher than those used in primates makes this drug a potentially effective agent in the systemic treatment of herpetic infections.